Metal finishing means and method for use of same



P 1962 M. c. SHAW ETAL 3,055,102

METAL FINISHING MEANS AND METHOD FOR USE OF SAME Filed Oct. 11, 1956WORK (( INVENTORS MILTON c. SHAW PRESCOTT A. SM\TH 6 F 4 YBYNATHAN H.COOK B /m 1% a4,

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Filed Oct. 11, 1956. Ser. No. 615,328 3 Claims. (Cl. 29-547) Thisinvention relates to the cold finishing of metal and it relates moreparticularly to a method and apparatus for the removal of metal and forthe finishing of metal bars, rods or wires.

As used herein, the term bars or rods is meant to relate to metalelements of uniform cross-section including bars of round, oval, square,or of other curvilinear or polygonal cross-section. Reference will bemade herein to the application of the invention for the cold finishingof round rods or wires but it will be understood that bars and rods ofother cross-sectional shapes may be employed. The term metal is meant toinclude the metals fabricated for industrial, commercial or structuraluse, such as rods or bars of steel, copper, brass, aluminum, titanium,magnesium and the like metals. While steel may be specifically mentionedin the following discussion, it should be understood that the inventionis equally applicable to other metals.

In the cold finishing of metal, such as steel bars or rods, use isgenerally made of a drawing or extrusion operation wherein the metal isadvanced through a die to effect reduction in cross-sectional area. Barsare also cold finished by turning and grinding operations which reducethe metal bar in size by metal removal.

To the present, removal of unsound or other metal from the surface of asteel bar or rod has been eifected by a machining or cutting operationseparate and apart from the drawing or extrusion step. Metal removal asby means of a cutting lathe is not only slow and expensive but itrequires the utilization of considerable amounts of additional labor andequipment and it requires utilization of a considerable amount of spacefor equipment and for the additional inventory that is required.

It is an object of this invention to provide a new and improved methodand apparatus for use in the cold finishing of metal and it is a relatedobject to provide a method and apparatus for the removal of metal in amanner which is substantially free of the objectionable features ofprocesses heretofore employed.

Another object of this invention is to provide a method and apparatusfor cold finishing metal at high speed and in an efficient andeconomical manner and it is a related object to provide a method andapparatus for producing a high finish on metal and to effect a reductionin cross-sectional area without the expenditure of space, labor andequipment heretofore required for equivalent results by processesheretofore employed.

These and other objects and advantages of this invention willhereinafter appear and for purposes of illustration, but not oflimitation, an embodiment of the invention is shown in the accompanyingdrawing in which FIGURE 1 is a sectional elevational view showing theessential features of an apparatus embodied in the practice of thisinvention;

FIGURE 2 is a perspective view of the apparatus as employed in the coldfinishing of metal rods;

FIGURE 3 is an enlarged sectional elevational view of the metal cuttingportion of the device shown in FIG- URE 1; and

FIGURE 4 is a modification of the apparatus shown in FIGURE 1.

, 3,055,102 Patented Sept. 25, 1962 In accordance with the practice ofthis invention, the unwanted metal is removed from the surface of thebar or rod in a rapid and efficient manner by advancing the bar or redcontinuously through a cutter which operates to shave the metal from theentire surface of the bar or rod as it is advanced therethrough. Onedifliculty which arises in the use of a shaving tool of this characterstems from the inability to hold the bar or rod properly centered withinthe die. As a result, the bar or rod tends to wander from one side tothe other of the die. This produces a wavy surface and sometimes the baror rod may wander so far to one side or the other that the shaving toolcuts into wanted metal, while unwanted metal on the opposite side stillremains on the bar or rod.

In addition to waviness, difliculties arise from the large amount ofchattering and longitudinal vibration that takes place as the work isadvanced in cutting relation through the shaving tool and from thegalling that appears to have taken place on the surface of the metalwhich has been advanced through the shaving tool. This galling givesrise to an objectionable appendage on the cutting edge, known in theworkshop as a built-up edge. The slufiing off of this appendage isresponsible for a torn surface on the metal. Chattering is evidenced bysurface roughness on the metal and Wear on the tool. Unless thesedifficulties are overcome along with waviness, the use of a shaving toolfor the rapid removal of unwanted metal from the surface of bars or rodscannot be adapted to commercial practice.

To some extent, the problem of Waviness has been overcome by the systemdescribed in the Weaver Patent No. 2,233,928, issued on March 4, 1941,and entitled Wire Shaving Process and Fixture. In accordance with theteaching of the Weaver patent, the wandering capabilities of the wireare restricted by the use of a system of dies for guiding and reducingin combination with a cutting die. Many problems have been experiencedin operation of the system of Weaver and the finish secured has beenfound wanting in many respects, especially when the system is used onbars and rods, as distinguished from wires. Galling is in fact so severewhen processing steel by the system of Weaver as to render the processcommercially impractical.

We have succeeded in overcoming many of the difiiculties previouslyexperienced in the process of continuously shaving metal from thesurface of a'metal bar, rod, tube or wire without excessive chattering,without excessive galling, and without excessive waviness. We havesucceeded in the development of a system capable of use commerciallyrapidly and efficiently to remove unwanted metal from the surfaces ofbars, rods, tubing or wire, and in the preparation of the surface of themetal for a subsequent drawing or extrusion operation. We have succeededin combining the metal cutting and metal drawing or extrusion operationsto provide for a continuous process in which metal removal is elfectedin a simple and efficient manner and in which metal drawing or extrusionis improved thereby to provide a unitary process which overcomes many ofthe difiiculties heretofore encountered in the cutting and drawingoperations separately carried out in metal finishing.

These objectives have been achieved by the combination which makes useof a shaving tool 10 immediately in advance of and in axial alignmentwith a draw or ex trusion die 12 with a space 14 in between beingconfined by a housing 16 and which makes use of a fluid 22 filling theconfined space 14 between the shaving tool It) and die 12. The housing16 can be provided with a single inlet 18a in communication with thespace 14 through which the fluid 22 can be supplied in an amount tomaintain the confined space between the cutter and die filled with thefluid, as illustrated in FIGURE 4 of the drawing, or the housing can beprovided with an inlet 13 and an outlet 29 in communication with theconfined space for the flow of fluid through the confined space betweenthe shaving tool and die, as illustrated in FIG- URE 1 of the drawing.It will be suflicient if fluid is supplied to the confined space withoutpressure, but the supply of fluid under pressure offers certainadvantages, and in the subsequent description of the invention referencewill be made to the use of pressure fluid as filling the confined space.It will be understood, however, that the concepts of this inventioninclude the use of fluid without pressure to fill the space between theshaving tool and die. The combination of a cutter and draw die withfluid under pressure acting on the elements in between operates toeffect removal of unwanted metal from the surfaces of the work and toetfect reduction in cross- Sectional area without longitudinalvibration, chattering or waviness while, at the same time, conditioningthe cutter and the die for their respective cutting and drawing orextrusion functions.

The ability of the fluid materially to affect chattering, longitudinalvibration, galling and wandering as the work passes continuously intooperative engagement with the cutting tool and the subsequent extrusionor draw die, and the ability of the lubricant to provide desiredlubrication both for the shaving or cutting operation and the drawing orextrusion operation, would indicate that the fluid reacts in combinationwith the forces existing be tween the work and die or cutter to centerthe work and to cushion the work with respect to the die and cutter. Itmay be that the fluid, preferably under pressure, flows to provide alayer of liquid between the work and the cutter or die, thereby to causethe work to float during passage through the cutter or die whereby thedesired lubrication is secured all around and whereby the work iscushioned in the cutter or die in a manner to minimize wandering orvibration during passage through the cutter or die. Whatever the reason,it has been found that the combination of a cutter and a draw orextrusion die with fluid filling the space in between provides anassembly capable of use commercially for rapid and eflicient removal ofunwanted metal concurrently with the drawing or extrusion operation forsize reduction or surface finish without development of the diflicultiesand objectionable features heretofore experienced.

With reference now to the cutting tool, use can be made of a tool havinga cutting edge 24 formed of high speed steel, ,sintered carbide or thelike. The angle defined by the axis of the tool and the slope of thewall 26 defining the bore through the tool, referred to hereinafter asthe clearance angle, can range from 1 to 15 degrees. Since lowerclearance angles tend to lead to galling, it is preferred to make use ofa clearance angle greater than 3 degrees and preferably within the rangeof 3 to 6 degrees.

The angle which the outer wall 28 of the tool makes with theperpendicular to the axis of the work, hereinafter referred to as therake angle, can range from 10 to 40 degrees. It is preferred to make useof a rake angle as large as possible consistent with the ability of thetool to resist chipping at the cutting edge. For carbide tools, it ispreferred to make use of a rake angle greater than degrees andpreferably within the range of 15 to 25 degrees. For tools formed ofhigh speed steels, it is preferred to make use of a rake angle greaterthan degrees and preferably within the range of to 40 degrees.

While it is not essential to provide a land or flat on the clearanceface, the tendency towards waviness can be reduced when the cutting toolis formed with a land which reduces the clearance for a length nogreater than 0.020 inch and preferably for a length within the range of0.004 to 0.014 inch.

Having described the essential features of the cutting combinationtherewith. A draw die or an extrusion die of conventional constructionmay be employed in which the draw die, for example, is of conventionalconstruction having a bell portion followed by an approach which leadsinto a bearing and a back relief section. Whether large reductions areto be taken or whether a finished reduction is to be taken, the draw orextrusion die 12 is mounted in the housing in endwise alignment with thecutting tool 16 and in closely spaced relation therewith. In thepreferred practice, the die can be spaced from the tool by as little as,4 inch or as much as A; or /2 inch without loss of control inoperation. Distances greater than A; to /2 inch can be used where moretime is desired for use of the fluid to cool the metal betweenoperational steps and to chemically react with the freshly cut surfaceof the metal to provide improved lubrication. The lubricatingcharacteristics of the fluid are sometimes enhanced by the reactionsavailable between the fluid and the metal which is freshly cut and in amore reactive state as compared to metal previously cut and exposed tothe atmosphere prior to lubrication.

A shaving tool which cuts the entire surface of a. bar at one time is aparticularly difficult tool to lubricate. The motion of chip tends tocarry the fluid away from the cutting edge when the fluid is appliedalong the tool face, while the motion of the finished work surface tendsto carry fluid introduced along the clearance face away from the cuttingedge. Fluid can be driven down the rake and clearance faces of the toolagainst these adverse chip and workpiece motions only when applied underhigh pressure. When a shaving tool is used in the conventional mannerthere is no way of supplying fluid under high pressure along either ofthe two faces. A free stream of fluid can only be supplied at highvelocity in order to make it penetrate which leads to much splashing andproves to be an impractical way of getting the fluid to penetrate to thecutting edge. By using a shaving tool and die simultaneously andconfining the space between the two, it is possible to supply fluid tothe clearance surface of the tool and to the front face of the die underpressure without great flow and a costly pumping loss. The cutting edgelimits the flow from one end of the confined space while the draw dietends to seal the other end. A desirable static pressure may bemaintained in the confined space between tool and die by a simple handpump. Or, the fluid in the confined space may be circulated by providingboth inlet and outlet connections, external piping and a suitablecirculating pump. The use of cutter and die with intervening spaceconfined makes it possible to obtain sufliciently high pressure at theclearance face of the tool to drive the fluid to the cutting edge andhence prevent formation of the build-up edge which makes ordinaryattempts to produce smooth skinned and drawn rods unsuccessful.

The fluid supplied to the confined space also tends to reducechattering, longitudinal vibration and wandering. In addition, thefluid, when circulated, can be used to extract heat from the metal tocool the metal during passage from the cutter to the die in process.Further, the fluid can be selected for imparting lubricatingcharacteristics to lubricate the cutting operation and to providelubrication for the draw or extrusion die, since fluid is forced underpressure into intimate communication between the surfaces of the workand the cutter and between the surfaces of the work and the draw orextrusion die. In the practice of this invention, use can be made ofphosphated fluids, Freons and other conventional drawing fluids.

As previously pointed out, the concepts of this invention are madeavailable but the use of fluids without pressure by flow of fluids toprovide all of the advantages described is best secured by the use offluids under positive pressure. In practice, the fluid can thus hesuptool, reference will now be made to the die 12 used in plied to fillthe confined space with the fluid under a pressure range from to 10,000pounds per square inch. The optimum range has been found to reside inthe use of fluid under a pressure within the range of 100 to 5,000pounds per square inch. Pressures greater than 10,000 pounds per squareinch can be employed but without proportional influence on lubrication,Waviness, chattering or longitudinal vibration. Pressures in the higherportion of the range described have been found to be beneficial where itis desirable to make greater reductions in the drawing or extrusionstep. In any event, pressure-s in excess of 10,000 pounds per squareinch would seldom be employed.

In the combination described, the depth of cut taken from the metal canrange from 0.001 to 0.020 inch depending upon the speed of the workthrough the die and the cross-sectional dimension of the work.Similarly, the amount of reduction will depend somewhat on these samefactors plus the type and pressure of the fluid and it may vary from afinished draft of 0.002 to 0.01 inch or a reduction draft of 0.002 to0.06 inch or more depending upon the albove factors. It will beunderstood that the concepts of this invention are not limited by thedepth of cut or the amount of reduction taken during passage through thedies. When like cuts are taken at low speeds, use can be made of toolshaving a larger rake angle limited only by the tendency for the tool tochip. In general, cutting speeds in the range of to 1000 feet or moreper minute can be employed for the combination of cutting and thedrawing or extrusion operation.

In one specific illustration, use was made of a cutting tool of highspeed steel having a 30 degree rake angle, a 5 degree clearance anglewith no flat on the clearance face. The tool was selected to provide adepth of cut within the range of 0.003 to 0.005 inch. The draw die,mounted ,4, inch from the cutter, was dimensioned to take a reduction of0.003 to 0.005 inch for finishing the metal. In another instance, thedraw die was dimensioned to take a larger reduction of about 0.06 inch.A phosphate drawing fluid or Freon 112 was supplied to the housingthrough the space between the dies at a pressure of about 1000 psi. Thework, a C1018 steel, was advanced through the system at a speed of 50feet per minute. In operation, the metal was shaved smoothly and at auniform depth from all around the rod and a finished piece of goodquality and appearance was produced.

It has been found that a tandem die system with fluid under pressureoperating upon the dies and upon the areas in between the dies iseffective also in the combination which makes use of a draw die orextrusion die in substitution for the cutter thereby to provide a tandemdraw die system in which one die can be selected for one reduction or invarious other combinations. It will be apparent also that the die systemmay be further extended to add more dies to the combination with aconfined spaced relation therebetween through which fluid under pressurecan be suplied but, when use is made of a cutter, location of the cutteris, for the present, limited to the head of the system only because ofthe difliculty otherwise of disposing of the chips. When means areprovided for disposal of chips, the system can make use of variouscombinations of dies and cutters in numerous arrangements.

It will be apparent from the foregoing that we have provided a new andimproved device for the cold finishing of metal bars and rods wherebymetal removal is effected in a simple and efiicient manner accurately toremove the unwanted metal from the surface of the bar or rod prior toimmediate and continuous entrance of the cut metal through a subsequentdie for processing as through a draw die or an extrusion die to effectreduction in cross-sectional area.

It will be understood that changes may be made in the details ofconstruction and operation of the device without departing from thespirit of the invention, especially as defined in the following claims.

We claim:

1. The method of cold finishing metal bars and rods, comprising thesteps of advancing the metal bars and rods continuously through ashaving tool dimensioned to have a rake angle within the range of 1.040degrees and a clearance angle Within the range of 1l5 degrees forshaving metal from the surfaces of the bars and rods advancedtherethrough and then through an extrusion die axially aligned with thecutting tool and spaced a short distance therefrom to effect a reductionin cross-sectional area, confining the space between the cutting tooland the extrusion die, and supplying lubricating fluid under highpressure to fill the confined space whereby fluid flows into the cuttingarea between the edge of the cutter and the work for stabilizing thecutting operation while simultaneously lubricating the freshly cutsurface of the metal during passage from the cutter through the die.

2. The method as claimed in claim 1 in which the fluid is a pressurefluid supplied to maintain the pressure within the confined space withinthe range of -10,000 pounds per square inch.

3. The method of cold finishing metal bars and rods, comprising thesteps of advancing the metal bars and rods continuously through ashaving tool dimensioned to have a rake angle within the range of 10-40degrees and a clearance angle within the range of 1-15 degrees forshaving metal from the surfaces of the bars and rods advancedtherethrough and then through a draw die axially aligned with thecutting tool and spaced a short distance therefrom to effect a reductionin cross-sectional area, confining the space between the cutting tooland the draw die, and supplying lubricating fluid under high pressure tofill the confined space whereby fluid flows into the cutting areabetween the edge of the cutter and the work for stabilizing the cuttingoperation while simultaneously lubricating the freshly cut surface ofthe metal during passage from the cutter through the die.

References Cited in the file of this patent UNITED STATES PATENTS1,896,674

